1. Field of the Invention
The present invention relates to the field of a contact lens and, more particularly, to a colored contact lens having iris-colored part onto the lens core, and a method for manufacturing thereof.
2. Description of the Relevant Art
Generally, many people desire to have beautiful eyes and more recently people desire more beautiful and natural eye colors. Every race has its peculiar iris color, which makes each face look different. Some people want to possess a unique eye color which is different from their natural eye color. However, cosmetics or other accessories are not satisfactory to them.
To satisfy this desire, there is provided a colored contact lens, which is made by coloring the portion of a contact lens which covers the iris. This colored contact lens may serve two purposes; improving eyesight and enhancing appearance at the same time.
Until now, many kinds of colored contact lenses have been developed and used by many manufacturers all over the world.
At first, as shown in FIG. 1, an opaque colored soft contact lens is developed from Titomus Eurocon Co. in Germany. To make this lens, the technique provides a lower lens 3 by polymerizing HEMA (2-Hydroxyethylmethacrylate) and then forms an iris-colored part 5 by individually and manually painting a desired iris color with an opaque dye or pigment on the lower lens 3.
Then, a transparent upper contact lens 7 made of HEMA is bonded to the lower lens 3 having the iris-colored part 5 to make the colored contact lens 1.
However, since the iris-colored part 5 is painted on the lower lens 3 by hand, a pair of lenses may have different colors due to a lack of reproduction. Additionally, since two lenses are put together, they are thicker, and thus uncomfortable to wear.
There is also proposed a coloring technique for an opaque colored soft contact lens from Wesley Jackson Co. in U.S. As shown in FIG. 2, this technique suggests a method of polymerizing HEMA to form a lens 13 and then forming a iris-colored part by drawing lines with innumerable dots on, the lens 13, thus making a colored contact lens 11.
In this technique, the iris-colored part 15 is directly formed on a surface of the lens. 13. Though attractive, such a configuration may cause friction between the inner side of an eyelid and the iris-colored part of the contact lens. Thus, this kind of conventional lens cannot be used for a long period of time because of the possibility of conjunctivitis or absorption of waste matter, such as proteins or lipids, around the iris-colored part.
There is also developed a colored soft lens technique by Sereko Co. in England as shown in FIG. 3. This technique first provides a mold, and then forms a lens 23 onto the mold, in which HEMA monomer is polymerized and forms a lens having an iris-colored part 25 where opaque dyes mixed with HEMA monomer are printed, and then cut the lens 23 to make a colored soft lens 21.
Although this method makes mass production possible since the mold is used to make the lens 23, this technique has a problem in that it causes discomfort to the wearer of the contact lens and even causes keratitis as the iris-colored part on the lower side of the lens rubs a cornea when blinking.